title: Inactivation of the polyketide synthase, 6-methylsalicylic acid synthase, by the specific modification of Cys-204 of the beta-ketoacyl synthase by the fungal mycotoxin cerulenin.
abstract: Cerulenin, [(2S,3R)-2,3-epoxy-4-oxo-7,10-dodecadienoylamide], a mycotoxin produced by Cephalosporium caerulens, irreversibly inactivated 6-methylsalicylic acid synthase from Penicillium patulum. A combination of radiolabelling studies with [3H]cerulenin, proteolytic and chemical digestion and N-terminal sequencing of labelled peptides indicated that the site of cerulenin modification is the highly reactive substrate-binding Cys-204 of the beta-ketoacyl synthase enzyme component. The thiol-specific inhibitor, iodoacetamide, was also shown to alkylate this residue. These findings are analogous with those observed for the reaction of cerulenin and iodoacetamide with type-I fatty acid synthases, demonstrating the close similarity between 6-methylsalicylic acid synthase and type-I fatty acid synthases.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southampton, Biomedical Sciences Building, Bassett Crescent East, Southampton SO16 7PX, U.K.
authors.forename: C J
authors.initials: CJ
authors.lastname: Child
authors.forename: P M
authors.initials: PM
authors.lastname: Shoolingin-Jordan
mesh_terms: D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase / Q000378:metabolism*; D000105:Acetyl Coenzyme A / Q000378:metabolism; D000217:Acyltransferases / Q000037:antagonists & inhibitors*; D000478:Alkylation; D000935:Antifungal Agents / Q000494:pharmacology*; D001667:Binding, Competitive; D002569:Cerulenin / Q000494:pharmacology*; D003488:Cyanogen Bromide / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism*; D007460:Iodoacetamide / Q000378:metabolism; D007700:Kinetics; D008025:Ligases / Q000037:antagonists & inhibitors*; D008316:Malonyl Coenzyme A / Q000378:metabolism; D008956:Models, Chemical; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors*; D010088:Oxidoreductases / Q000037:antagonists & inhibitors*; D010407:Penicillium; D010449:Peptide Mapping; D012697:Serine Endopeptidases / Q000378:metabolism; D013211:Staphylococcus aureus
chemical_list: D000935:Antifungal Agents; D009097:Multienzyme Complexes; D002569:Cerulenin; D008316:Malonyl Coenzyme A; D000105:Acetyl Coenzyme A; D010088:Oxidoreductases; D000217:Acyltransferases; D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; C021587:6-methylsalicylic acid synthetase; D008025:Ligases; D003545:Cysteine; D003488:Cyanogen Bromide; D007460:Iodoacetamide